In a semiconductor device fabrication process, a wafer having a device area with a plurality of devices partitioned by a plurality of division lines is divided into individual dies or chips along the division lines.
Substantially the same approach as detailed above is also adopted to obtain, for example, individual power devices, optical devices, medical devices, electrical components or MEMS devices from wafers with device areas, in which these devices are formed.
In order to reduce the strength of the wafer along the division lines prior to dividing the wafer, it is known to form a modified region in the wafer along the division lines. This modified region may be in the form of a modified layer formed inside the wafer or in the form of a plurality of hole regions, wherein each hole region is composed of an amorphous region and a space in the amorphous region open to at least one surface of the wafer. Such a modified region is formed by applying a laser beam with a suitable wavelength to the wafer along the division lines.
After the modified region has been formed in the wafer along the division lines, an external force is applied to the wafer in the radial directions thereof, thereby dividing the wafer along the division lines and separating the resulting dies or chips from each other. In particular, the wafer may be attached to an expandable tape and the external force may be applied thereto by radially expanding the tape.
Alternatively, the wafer may be divided along the division lines into the individual dies or chips, for example, by mechanical cutting, laser cutting or applying a plasma to the wafer. Prior to this dividing process, the wafer may be attached to a tape, such as an adhesive tape.
Subsequently, after dividing the wafer into the individual dies or chips, the separated dies or chips may be picked up from the tape. Alternatively, the dies or chips are kept on the tape and, in this state, subjected to further processing, stored or shipped. When keeping the separated dies or chips attached to the tape, it is important to maintain radial tension of the tape, in order to prevent damage to the dies or chips due to any unintentional contact therebetween.
DE 10 2010 046 665 A1 discloses a method of processing a wafer in which, after separating dies from each other by radially expanding an expandable tape, a ring-shaped tape is attached to a peripheral portion of the expanded tape, so as to keep the expanded tape under radial tension. The ring-shaped tape is supported by an annular frame.
However, the approach taught in DE 10 2010 046 665 A1 requires the preparation of an annular frame with a suitably adapted ring-shaped tape attached thereto and is thus laborious and time-consuming. Since the tape has to be cut into an appropriate ring shape, there are significant material losses, resulting in increased processing costs. Also, the characteristics of the ring-shaped tape have to be precisely matched with those of the expandable tape, thus restricting the choice of possible tape materials. Further, the tension of the ring-shaped tape may decrease over time, creating the risk of unintentional contact between the dies, e.g., during storage or shipping thereof.
Hence, there remains a need for a method of processing a wafer and a wafer processing system which allow for the wafer to be processed in an efficient, reliable and cost-efficient manner.